IP address is a personal address peculiar to a certain system or gadget and with the little I know about internet, I believe a phone and computer cannot have same IP address. The only thing that I might not be able to ascertain is the fact that, if the internet system on them is the same.
However, there is some circumstance that I've noticed with some IP address manipulations by ways of cracking a gadgets inbuilt network and OPS, such that it can be done that both of the gadgets bears the same address.
Some internet advancement has moved to the extent that an IP address can now be manipulated by some persons to change location of the gadget or even hide the address from viewing it.
So, in an ordinary system it can't be possible but in an advance system it goes but i doubt if answeree encourages that without blocking the account.